The high Tc superconducting bolometer

A description is given of the optimization of a bolometric infrared detector which uses the resistive transition of a high-T _c film as the thermometer. The performance of an LN (Liquid nitrogen)-cooled far-infrared bolometer operated with a cooled low-pass filter is computed for the ideal case of a noise-free readout. The theory is then extended to include various contributions to the readout noise. Measurements are presented of the low frequency noise near T_c in current-biased films of ErBa₂Cu₃O₇, which show that useful performance can be achieved. Comparisons are made with other infrared detection technologies which show that practical high T_c bolometers will be especially useful for wavelengths longer than the -20 μm cutoff of LN-cooled photovoltaic detectors. Potential applications include far-infrared laboratory spectroscopy and passively cooled space observations of bright sources such as the earth